Ganglion cyst

The origin of ganglion cysts is unclear but they are commonly associated with degenerative conditions of soft tissue or bone. They may occur adjacent to joints, tendons, fascial planes, and within bone.

Most ganglion cysts can be definitively diagnosed based on a careful history and physical examination. By history the lesion has a tendency to both increase and decrease in size over time. On exam, ganglion cyst typically has superficial location, and may be adjacent to a joint. When these lesions occur near a joint, there is often osteoarthritis seen on the xray. The mass is soft when the nearby joint is relaxed, and becomes firm when the nearby joint or muscle is tensed. A pen light or a small laser pointer will transilluminate the cyst.

If the initial assessment yields the expected results, one attempt at aspiration with a large bore needle should be performed. Aspiration of the characteristic clear viscous material from the mass confirms the diagnosis. If the characteristic fluid is not obtained, no further attempts should be made.

An MRI should be obtained to further delineate the mass. Ganglion cyst has a characteristic MRI appearance. The lesion is well-defined, lobular and homogeneous, with low signal intensity on T1 sequences and high signal intensity on T2 sequences typical of water or fluid.

Once confirmed, the cyst may be treated with aspiration and injection with cortisone, which should lead to resolution in about half the cases. Surgical removal is indicated for persistent, large or troublesome cysts. The mass should explored and the origin of the cyst and the stalk identified, if possible. A portion of the joint capsule and the stalk should be excised in continuity with the mass. Loupe magnification and tourniquet hemostasis will assist in visualization of the stalk and may decrease the risk of recurrence. Approximately 10% of these cysts recur following surgery.

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